A false twisting apparatus in which two belts are travelled in directions opposite to each other and a yarn is nipped between the two belts to false-twist the yarn has been known. More specifically, in this known false twisting apparatus, two flexible belts are travelled in directions opposite to each other so that they intersect each other at a predetermined angle of intersection, and by nipping a yarn between the two belts, a component of the force for travelling the belts is divided into a force for turning the yarn and a force for feeding out the yarn, whereby the yarn is false-twisted.
In such belt-type false twisting apparatus, at the point of intersection, the two belts are compressed to each other through face-to-face contact and a yarn is nipped at such point of intersection between the two belts. In this case, false twisting of the yarn is performed relatively stably. However, since the belts are travelled in opposite directions with a certain angle of intersection, friction is caused between the contact surfaces of the belts, and the lives of the belts are shortened unless a lubricant such as water or an oiling agent is always supplied to the contact surfaces.
Furthermore, since the yarn nipped at the point of intersection of the belts is held between the contact surfaces of the belts along a length longer than the width of the belts, the nip point, that is, the twisting point, is perpetually changed, and the distances of the twisting zone and untwisting zone are not kept constant. Accordingly, if the twisting point shifts to the twisting side, an excessively untwisted portion is formed on the yarn. On the contrary, if the twisting point shifts to the untwisting side, a non-untwisted portion is formed on the yarn. Therefore, a uniformly false-twisted yarn cannot be obtained and the quality of the product yarn is degraded.
Furthermore, there is known a false twisting unit in which in order to facilitate the operation of passing a yarn through a portion where belts intersect each other, a bracket supporting pulleys on which the belts are hung is disposed so that the bracket can turn with one axis being as the fulcrum. In this false twisting unit, means for positioning the bracket should additionally be disposed, and the bracket is shaken by a yarn running at a high speed and the contact pressure between the belts is readily changed at the twisting point, with the result that uneven twisting is often caused.